About Optics & Photonics TopicsOSA Publishing developed the Optics and Photonics Topics to help organize its diverse content more accurately by topic area. This topic browser contains over 2400 terms and is organized in a three-level hierarchy. Read more.

Topics can be refined further in the search results. The Topic facet will reveal the high-level topics associated with the articles returned in the search results.

Abstract

We report forward and backward THz-wave difference frequency generations at 197 and 469 μm from a PPLN rectangular crystal rod with an aperture of 0.5 (height in z) × 0.6 (width in y) mm2 and a length of 25 mm in x. The crystal rod appears as a waveguide for the THz waves but as a bulk material for the optical mixing waves near 1.54 μm. We measured enhancement factors of 1.6 and 1.8 for the forward and backward THz-wave output powers, respectively, from the rectangular waveguide in comparison with those from a PPLN slab waveguide of the same length, thickness, and domain period under the same pump and signal intensity of 100 MW/cm2.

Figures (3)

(a) Photograph of the three 2-D NOSWs fabricated from PPLN for our experiment. Experimental data in this paper were taken from the longest one. (b) Schematic of the forward and backward THz-wave DFG in PPLN NOSW. The pump and signal are initially combined from a distributed feed-back diode laser (DFBDL) and a tunable external cavity diode laser (ECDL), and then boosted up in power by an Erbium-doped fiber amplifier (EDFA) and a pulsed optical parametric amplifier (OPA). A 4K silicon bolometer detects the backward and forward THz waves before and after the PPLN NOSW, respectively.

(a) Measured forward THz-wave tuning curves from the 1-D (dots) and 2-D (crosses) PPLN NOSWs. The dashed and continuous lines are fitting curves of Eq. (4) with Γ = 0.53 and 0.65 cm−1 for the 1-D and 2-D NOSW, respectively, given an attenuation coefficient of 40 cm−1. (b) The Measured THz-wave output power versus pump intensity from the 1-D (squares) and 2-D (circles) NOSWs, indicating some nonlinear THz-wave power enhancement in the 2-D NOSW.

(a) Measured backward THz-wave tuning curves from the 1-D (dots) and 2-D (crosses) PPLN NOSWs. The dashed and continuous lines are fitting curves of Eq. (7) with Γ = 0.34 and 0.44 cm−1 for the 1-D and 2-D NOSWs, respectively, and with an assumed attenuation coefficient of 6 cm−1. (b) The Measured backward THz-wave output power versus pump intensity from the 1-D (squares) and 2-D (circles) NOSWs, indicating enhanced THz-wave power from the 2-D NOSW over the whole range of measurement.